A nut riveter is a tool used for riveting industrial nuts, can rivet nuts on plates and is widely used. For example, Chinese Patent No. 201010588266.4 discloses a nut riveter, which comprises a riveter seat, a nut adjusting mechanism arranged at a front end of the riveter seat, a nut riveting rod installed in the nut adjusting mechanism, two handles with front ends which are respectively hinged with the riveter seat through first pin shafts and fitting holes in two sides of the riveter seat, and a pull rod retractable mechanism connected to a pull rod, wherein the nut riveting rod is fixed at a front end of the pull rod; the nut riveter further comprises a screw rod with one end which is connected with the pull rod retractable mechanism through a sixth pin shaft and a screw rod outer sleeve with one end which is fixed on the pull rod retractable mechanism through threads, wherein the screw rod is arranged in a cavity of the screw rod outer sleeve; a push rod sleeves a position between the screw rod and the screw rod outer sleeve, steel balls fit with a screw groove in the screw rod are inlaid in one end of the push rod, a one-way clutch sleeves the other end of the push rod and the one-way clutch is fixed in a clutch seat; the clutch seat is connected with a withdrawing connecting rod through a fifth pin shaft and the withdrawing connecting rod is connected onto the handles through fourth pin shafts; the pull rod retractable mechanism comprises a pull rod seat, a fixed nut, second pin shafts, connecting rods and third pin shafts; the pull rod penetrates through the pull rod seat and a tail end of the pull rod is fixed on the fixed nut; the fixed nut is located in a chamber of the pull rod seat and a tail portion of the fixed nut is connected with the screw rod through the sixth pin shaft; and one end of the connecting rod is hinged with the front end of the handle through the second pin shaft and the other end of the connecting rod is connected with the pull rod through the third pin shaft.
The nut riveter in by the above-mentioned art provides improved nut riveting efficiency by riveting nuts based on the lever principle. However, the following problems often exist with conventional riveter: since the front ends of the handles are connected with the riveter seat through fastening pieces, the two handles must be pulled outwards first, and then inwards in order the grip the nut. The second pin shafts can be viewed as fulcrums of the lever principle. As the force in power arms are continuously reduced, the forced need in the resisting arms are continuously increased when the two handles are approaching each other. Consequently the force need to operate the riveter is gradually increased.
For smaller nuts, the force needed during riveting is smaller. The above-mentioned solution may be sufficient. However, for large nuts, more force is needed. In addition, when the two handles come closer to each other, the continuously increasing force may feel laborious and strenuous to its users. Particularly for people with less physical strength, the nut riveter may be hard to use. Therefore, a larger nut riveter is needed for large nuts. However, nuts of different sizes are often riveted within a short period of time during one particular operation. As a result, several nut riveters need to be carried and frequently changed during use and it is troublesome in use.
As a result, there is a need for a labor-efficient riveter that can accommodate nuts of different sizes.